Sample Question Paper 2020-21 Science (086) Theory . - CBSE

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Sample Question Paper 2020-21Class XScience (086) TheoryTime: 3 HoursMaximum Marks: 80General Instructions:(i) The question paper comprises four sections A, B, C and D. There are 36 questions inthe question paper. All questions are compulsory.(ii) Section–A - question no. 1 to 20 - all questions and parts thereof are of one mark each.These questions contain multiple choice questions (MCQs), very short answerquestions and assertion - reason type questions. Answers to these should be given inone word or one sentence.(iii) Section–B - question no. 21 to 26 are short answer type questions, carrying 2 markseach. Answers to these questions should in the range of 30 to 50 words.(iv) Section–C - question no. 27 to 33 are short answer type questions, carrying 3 markseach. Answers to these questions should in the range of 50 to 80 words.(v) Section–D – question no. - 34 to 36 are long answer type questions carrying 5 markseach. Answer to these questions should be in the range of 80 to 120 words.(vi) There is no overall choice. However, internal choices have been provided in somequestions. A student has to attempt only one of the alternatives in such questions.(vii) Wherever necessary, neat and properly labeled diagrams should be drawn.SECTION ANo.QuestionsMarks1List any two observations when Ferrous Sulphate is heated in a dry test tube?ORIdentify the products formed when 1 mL of dil. Hydrochloric acid is added to1g of Sodium metal?12Write the chemical name and chemical formula of the salt used to removepermanent hardness of water.13Which of the following is not observed in a homologous series? Give reasonfor your choice.a) Change in chemical propertiesb) Difference in -CH2 and 14u molecular massc) Gradation in physical propertiesd) Same functional group14Why does the Sun appear white at noon?11

5Both a spherical mirror and a thin spherical lens have a focal length of (-)15cm. What type of mirror and lens are these?16The image formed by a concave mirror is observed to be real, inverted andlarger than the object. Where is the object placed?ORName the part of a lens through which a ray of light passes without sufferingany deviation.17In the arrangement shown in figure there are two coils wound on a nonconducting cylindrical rod. Initially the key is not inserted in the circuit. Laterthe key is inserted and then removed shortly after.1What are the two observations that can be noted from the galvanometerreading?8Draw the magnetic field lines around a straight current carrying conductor.19Two unequal resistances are connected in parallel. If you are not provided withany other parameters (eg. numerical values of I and R), what can be said aboutthe voltage drop across the two resistors?ORSome work is done to move a charge Q from infinity to a point A in space. Thepotential of the point A is given as V. What is the work done to move thischarge from infinity in terms of Q and V?110Veins are thin walled and have valves. Justify.111How is the wall of small intestine adapted for performing the function ofabsorption of food?OROut of a goat and a tiger, which one will have a longer small intestine? Justifyyour answer.112Explain how ozone being a deadly poison can still perform an essentialfunction for our environment.ORGive reason why a food chain cannot have more than four trophic levels.12

13State the role of pancreas in digestion of food.1For question numbers 14, 15 and 16, two statements are given- one labeled Assertion (A) and theother labeled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c)and (d) as given below:a) Both A and R are true, and R is correct explanation of the assertion.b) Both A and R are true, but R is not the correct explanation of the assertion.c) A is true, but R is false.d) A is false, but R is true.14Assertion: After white washing the walls, a shiny white finish on walls is 1obtained after two to three days.Reason: Calcium Oxide reacts with Carbon dioxide to form CalciumHydrogen Carbonate which gives shiny white finish.15Assertion: Food chain is responsible for the entry of harmful chemicals in our 1bodies.Reason: The length and complexity of food chains vary greatly.ORAssertion: Greater number of individuals are present in lower trophic levels.Reason: The flow of energy is unidirectional.16Assertion: A geneticist crossed a pea plant having violet flowers with a pea 1plant with white flowers, he got all violet flowers in first generation.Reason: White colour gene is not passed on to next generation.Answer Q. No 17 - 20 contain five sub-parts each. You are expected to answer any four subparts in these questions.17Read the following and answer any four questions from 17 (i) to 17 (v)1x4All living cells require energy for various activities. This energy is available bythe breakdown of simple carbohydrates either using oxygen or without usingoxygen.(i) Energy in the case of higher plants and animals is obtained bya) Breathingb) Tissue respirationc) Organ respirationd) Digestion of food(ii) The graph below represents the blood lactic acid concentration of an athleteduring a race of 400 m and shows a peak at point D.3

Lactic acid production has occurred in the athlete while running in the 400m race. Which of the following processes explains this event?a) Aerobic respirationb) Anaerobic respirationc) Fermentationd) Breathing(iii) Study the graph below that represents the amount of energy supplied withrespect to the time while an athlete is running at full speed.Choose the correct combination of plots and justification provided in thefollowing table.4

Plot APlot BJustificationa)AerobicAnaerobicAmount of energy is low and inconsistentin aerobic and high in anaerobicb)AerobicAnaerobicAmount of energy is high and consistentin aerobic and low in anaerobicc)AnaerobicAerobicAmount of energy is high and consistentin aerobic and low in anaerobicd)AnaerobicAerobicAmount of energy is high and inconsistentin anaerobic and low in aerobic(iv) The characteristic processes observed in anaerobic respiration arei) presence of oxygenii) release of carbon dioxideiii) release of energyiv) release of lactic acida)b)c)d)i) ,ii) onlyi), ii), iii) onlyii), iii), iv) onlyiv) only(v) Study the table below and select the row that has the incorrect itochondriab)End ProductCO2 and H20Ethanol and CO2c)Amount of ATP HighLowd)OxygenNot neededNeededRead the following and answer any four questions from 18 (i) to 18 (v).Metallic CharacterThe ability of an atom to donate electrons and form positive ion (cation) is 1x 4known as electropositivity or metallic character. Down the group, metalliccharacter increases due to increase in atomic size and across the period, from5

left to right electropositivity decreases due to decrease in atomic size.Non-Metallic CharacterThe ability of an atom to accept electrons to form a negative ion (anion) iscalled non-metallic character or electronegativity. The elements having highelectro-negativity have a higher tendency to gain electrons and form anion.Down the group, electronegativity decreases due to increase in atomic size andacross the period, from left to right electronegativity increases due to decreasein atomic size.18 (i)Which of the following correctly represents the decreasing order of metalliccharacter of Alkali metals plotted in the graph?a) Cs Rb Li Na Kb) K Rb Li Na Csc) Cs Rb K Na Lid) Cs K Rb Na Li18 (ii)Hydrogen is placed along with Alkali metals in the modern periodic tablethough it shows non-metallic charactera) as Hydrogen has one electron & readily loses electron to form negativeionb) as Hydrogen can easily lose one electron like alkali metals to formpositive ionc) as Hydrogen can gain one electron easily like Halogens to formnegative iond) as Hydrogen shows the properties of non-metals18 (iii) Which of the following has highest electronegativity?a) Fb) Clc) Brd) I6

18 (iv) Identify the reason for the gradual change in electronegativity in halogensdown the group.a) Electronegativity increases down the group due to decrease in atomicsizeb) Electronegativity decreases down the group due to decrease intendency to lose electronsc) Electronegativity decreases down the group due to increase in atomicradius/ tendency to gain electron decreasesd) Electronegativity increases down the group due to increase in forces ofattractions between nucleus & valence electrons18 (v)19Which of the following reason correctly justifies that “Fluorine (72pm) hassmaller atomic radius than Lithium (152pm)”?a) F and Li are in the same group. Atomic size increases down the groupb) F and Li are in the same period. Atomic size increases across theperiod due to increase in number of shellsc) F and Li are in the same group. Atomic size decreases down the groupd) F and Li are in the same period and across the period atomic size/radiusdecreases from left to right.Read the following and answer any four questions from 19 (i) to 19 (v)Sumati wanted to see the stars of the night sky. She knows that she needs atelescope to see those distant stars. She finds out that the telescopes, which are 1x 4made of lenses, are called refracting telescopes and the ones which are made ofmirrors are called reflecting telescopes.So she decided to make a refracting telescope. She bought two lenses, L1 andL2. out of which L1 was bigger and L2 was smaller. The larger lens gathers andbends the light, while the smaller lens magnifies the image. Big, thick lensesare more powerful. So to see far away, she needed a big powerful lens.Unfortunately, she realized that a big lens is very heavy.Heavy lenses are hard to make and difficult to hold in the right place. Also7

since the light is passing through the lens, the surface of the lens has to beextremely smooth. Any flaws in the lens will change the image. It would belike looking through a dirty window.19 (i)Based on the diagram shown, what kind of lenses would Sumati need to makethe telescope?a) Concave lensesb) Convex lensesc) Bifocal lensesd) Flat lenses19 (ii)If the powers of the lenses L1 and L2 are in the ratio of 4:1, what would be theratio of the focal length of L1 and L2?a) 4:1b) 1:4c) 2:1d) 1:119 (iii) What is the formula for magnification obtained with a lens?a) Ratio of height of image to height of objectb) Double the focal length.c) Inverse of the radius of curvature.d) Inverse of the object distance.19 (iv) Sumati did some preliminary experiment with the lenses and found out that themagnification of the eyepiece (L2) is 3. If in her experiment with L2 she foundan image at 24 cm from the lens, at what distance did she put the object?a) 72 cmb) 12 cmc) 8 cmd) 6 cm19 (v)Sumati bought not-so-thick lenses for the telescope and polished them. Whatadvantages, if any, would she have with her choice of lenses?a) She will not have any advantage as even thicker lenses would giveclearer images.b) Thicker lenses would have made the telescope easier to handle.c) Not-so-thick lenses would not make the telescope very heavy and alsoallow considerable amount of light to pass.d) Not-so-thick lenses will give her more magnification.8

20Read the following and answer any 4 questions from 20 (i) to 20 (v).A solenoid is a long helical coil of wire through which a current is run inorder to create a magnetic field. The magnetic field of the solenoid is thesuperposition of the fields due to the current through each coil. It is nearlyuniform inside the solenoid and close to zero outside and is similar to the fieldof a bar magnet having a north pole at one end and a south pole at the otherdepending upon the direction of current flow. The magnetic field produced inthe solenoid is dependent on a few factors such as, the current in the coil,number of turns per unit length etc.The following graph is obtained by a researcher while doing an experiment tosee the variation of the magnetic field with respect to the current in thesolenoid.The unit of magnetic field as given in the graph attached is in milli-Tesla (mT)and the current is given in Ampere.20 (i)What type of energy conversion is observed in a linear solenoid?a. Mechanical to Magneticb. Electrical to Magneticc. Electrical to Mechanicald. Magnetic to Mechanical20 (ii)What will happen if a soft iron bar is placed inside the solenoid?a. The bar will be electrocuted resulting in short-circuit.b. The bar will be magnetised as long as there is current in the circuit.c. The bar will be magnetised permanently.d. The bar will not be affected by any means.420 (iii) The magnetic field lines produced inside the solenoid are similar to that of a. a bar magnet9

b. a straight current carrying conductorc. a circular current carrying loopd. electromagnet of any shape20 (iv) After analysing the graph a student writes the following statements.I.The magnetic field produced by the solenoid is inversely proportionalto the current.II.The magnetic field produced by the solenoid is directly proportional tothe current.III.The magnetic field produced by the solenoid is directly proportional tosquare of the current.IV. The magnetic field produced by the solenoid is independent of thecurrent.Choose from the following which of the following would be the correctstatement(s).a. Only IVb. I and III and IVc. I and IId. Only II20 (v)From the graph deduce which of the following statements is correct.a. For a current of 0.8A the magnetic field is 13 mTb. For larger currents, the magnetic field increases non-linearly.c. For a current of 0.8A the magnetic field is 1.3 mTd. There is not enough information to find the magnetic fieldcorresponding to 0.8A current.SECTION B21Bile juice does not have any digestive enzyme but still plays a significant rolein the process of digestion. Justify the statement.ORIn birds and mammals the left and right side of the heart are separated. Givereasons.222State the events occurring during the process of photosynthesis. Is it essentialthat these steps take place one after the other immediately?223Give a test that can be used to confirm the presence of carbon in a compound.With a valency of 4, how is carbon able to attain noble gas configuration in itscompounds?ORThe number of carbon compounds is more than those formed by all otherelements put together. Justify the statement by giving two reasons.210

24The following observations were made by a student on treating four metals P,Q, R and S with the given salt O4(aq)PNo reactionReactionoccursReactionoccursNo sReactionoccursRNo ReactionReactionOccursNo ReactionNo ReactionSNo ReactionNo ReactionNo ReactionNo Reaction2Based on the above observations:(a) Arrange the given samples in the increasing order of reactivity(b) Write the chemical formulae of products formed when Q reacts withCuSO4 solution.25A student observes the above phenomenon in the lab as a white light passesthrough a prism. Among many other colours, he observed the position of thetwo colours Red and Violet.What is the phenomenon called? What is the reason for the violet light to bendmore than the red light?211

262A student has two resistors- 2 Ω and 3 Ω. She has to put one of them in placeof R2 as shown in the circuit. The current that she needs in the entire circuit isexactly 9A. Show by calculation which of the two resistors she should choose.Section C27After self-pollination in pea plants with round, yellow seeds, following typesof seeds were obtained by Mendel:SeedsNumberRound, yellow630Round, green216Wrinkled, yellow202Wrinkled, green643Analyse the result and describe the mechanism of inheritance which explainsthese results.ORIn humans, there is a 50% probability of the birth of a boy and 50 %probability that a girl will be born. Justify the statement on the basis of themechanism of sex-determination in human beings.28Plastic cups were used to serve tea in trains in early days- these could bereturned to the vendors, cleaned and reused. Later,Kulhads were used insteadof plastic cups. Now, paper cups are used for serving tea.What are the reasons for the shift from Plastic to Kulhads and then finally topaper cups?329Explain where and how urine is produced?312

30a. Which of the following reactions is/ are an endothermic reaction(s) wheredecomposition also happens? Respiration Heating of lead nitrate Decomposition of organic matter Electrolysis of acidified water3b. Silver chloride when kept in the open turns grey. Illustrate this with abalanced chemical equation.31The following table shows the position of five elements A, B, C, D and E inthe modern periodic table.Group Period 12A32D3 to 12 131415161718BC3EAnswer the following giving reasons:(i) Which element is a metal with valency two?(ii) Which element is least reactive?(iii) Out of D and E which element has a smaller atomic radius?32a. Explain the formation of Calcium Chloride with the help of electron dotstructure. (At numbers: Ca 20; Cl 17)b. Why do ionic compounds not conduct electricity in solid state but conductelectricity in molten and aqueous state?333Refractive index of water with respect to air is 1.33 and that of diamond is2.42.(i) In which medium does the light move faster, water or diamond?(ii) What is the refractive index of diamond with respect to water?3Section D34Match the following pH values 1, 7, 10, 13 to the solutions given below: Milk of magnesia Gastric juices Brine Aqueous Sodium hydroxide.Amit and Rita decided to bake a cake and added baking soda to the cake batter.513

Explain with a balanced reaction, the role of the baking soda. Mention anyother use of baking soda.OR(i) Four samples A, B, C and D change the colour of pH paper or solution toGreen, Reddish-pink, Blue and Orange. Their pH was recorded as 7, 2, 10.5 &6 respectively. Which of the samples has the highest amount of Hydrogen ionconcentration? Arrange the four samples in the decreasing order of their pH.(ii) Rahul found that the Plaster of Paris, which he stored in a container, hasbecome very hard and lost its binding nature. What is the reason for this? Also, write a chemical equation to represent the reaction taking place.(iii) Give any one use of Plaster of Paris other than for plastering orsmoothening of walls.35Trace the changes that take place in a flower from gamete formation to fruitformation.536In the given circuit, A, B, C and D are four lamps connected with a battery of60V.5Analyse the circuit to answer the following questions.(i) What kind of combination are the lamps arranged in (series or parallel)?(ii) Explain with reference to your above answer, what are the advantages (anytwo) of this combination of lamps?(iii) Explain with proper calculations which lamp glows the brightest?(iv) Find out the total resistance of the circuit.ORPQ is a current carrying conductor in the plane of the paper as shown in thefigure below.14

(i) Find the directions of the magnetic fields produced by it at points R and S?(ii) Given r1 r2, where will the strength of the magnetic field be larger? Givereasons.(iii) If the polarity of the battery connected to the wire is reversed, how wouldthe direction of the magnetic field be changed?(iv) Explain the rule that is used to find the direction of the magnetic field for astraight current carrying conductor.15

Sample Question Paper 2020-21 Class X Science (086) Theory Time: 3 Hours Maximum Marks: 80 General Instructions: (i) The question paper comprises four sections A, B, C and D. There are 36 questions in the question paper. All questions are compulsory. (ii) Section–A - question no. 1 to 20 - all questions and parts thereof are of one mark each. .

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